1. Field of the Invention
The present invention relates to a method for patterning a thin film on a substrate, and more particularly to a method for patterning a dual damascene structure in a thin film on a substrate.
2. Description of Related Art
In material processing methodologies, pattern etching comprises the application of a thin layer of light-sensitive material, such as photo-resist, to an upper surface of a substrate that is subsequently patterned in order to provide a mask for transferring this pattern to the underlying thin film on a substrate during etching. The patterning of the light-sensitive material generally involves exposure by a radiation source through a reticle (and associated optics) of the light-sensitive material using, for example, a photo-lithography system, followed by the removal of the irradiated regions of the light-sensitive material (as in the case of positive photo-resist), or non-irradiated regions (as in the case of negative resist) using a developing solvent. Moreover, this mask layer may comprise multiple sub-layers.
More recently, in order to meet the increasing demand to produce smaller features, the use of multi-layer masks has become more prevalent. By utilizing a multi-layer mask, the top mask layer, which comprises a light-sensitive material as described above, may be thinner and, hence, a smaller feature size may be achieved using conventional photo-lithography techniques. However, in order to generate a mask layer of sufficient thickness for the ensuing primary etch process, additional material layers are formed underlying the top mask layer. The pattern, formed in the top mask layer using lithographic techniques, is transferred to the underlying layer or layers that comprise the mask layer for the primary etch process using dry processing, such as additional etching processes.